A question in Linear Momentum

1. The problem statement, all variables and given/known data
A piece of wood mass of 10 kilograms Placed on a smooth surface.
15 bullets were fired towards the piece and stabilized in .
The mass of one bullet is 40 grams and its velocity is 1000 meters in second.
Find the velocity of the piece of wood after the 15 bullets were stabilized in .

Actually this is not a homework question, and I am not studying a physics course. I am mathematician not physician. so why did I post the question ? The answer is that i was asked to convent my sisters daughter in the solution of her teacher.

Actually this is not a homework question, and I am not studying a physics course. I am mathematician not physician. so why did I post the question ? The answer is that i was asked to convent my sisters daughter in the solution of her teacher.

After the first bullet, if you were doing it serially, you have the momentum of the first in the block and it would be moving forward subsequently with the momentum imparted by the first and it would then add to the momentum of the second to become the new momentum of block and 2 bullets. And so on. And so on to the 15th that would be insinuating itself into a block that already had the momentum of the first 14.